As prior-art yarn package forming machines for winding a yarn treated by the yarn drawing and false-twisting machines on a bobbin, there have so far been provided a wide variety of machines represented by a frictional contact driving type of yarn package forming machine which comprises a stationary frame structure, a pair of supporting arms rockably supported on the stationary frame structure, a pair of bobbin holders each rotatably supported on each of the supporting arms to hold the bobbin, and a friction roller driven to rotate. The supporting arms are rockable between a first angular position where the bobbin is held in frictional contact with the friction roller to have the yarn wound thereon until the yarn is fully wound to be formed into a full yarn package on the bobbin, and a second angular position where the yarn package is held out of frictional contact with the friction roller.
In the conventional yarn package forming machine thus constructed, the yarn is firstly brought onto a bobbin formed with a slit at one of its axial end portions to have the leading end tail of the yarn pressed into the slit so that the leading end tail of the yarn is hooked and firmly gripped by the axial end portion of the bobbin. The yarn is then wound on the bobbin while being traversed within a traverse width until it is formed into a full yarn package (hereinafter simply referred to as a yarn package). After the yarn package is formed, the yarn is wound on the axial predetermined position of the yarn package by several turns to form a top bunch winding portion (hereinafter simply referred to as a bunch winding portion) thereon after the yarn is released from the traverse motion of a traverse guide and not kept at a standstill along the axis of the bobbin. The yarn is then cut by a cutter to form a trailing end tail. The trailing end tail of the yarn of the yarn package thus formed will be tied with the leading end tail of a yarn of another yarn package generally called "a pig tail" so that both the end tails of the yarns wound on the bobbins can be connected with each other, thereby enabling a plurality of yarn packages to be continuously treated in the following processes while the yarn is being continuously unwound from the yarn packages. As this type of yarn package forming machine for forming the bunch winding portion on the yarn package, there are proposed various yarn package forming machines such as for example those disclosed in Japanese Patent Publication Nos. 5-85669, 6-16335 and 6-299417. These conventional machines each comprises a bunch winding imparting guide for guiding a yarn into an area where the yarn can be wound into the bunch winding portion on the yarn package, a cutter for cutting the yarn after the bunch winding portion is completed on the yarn package, and a plurality of actuators like air cylinders and solenoids to independently actuate the bunch winding imparting guide and the cutter. Any of these conventional machines, however, have neither means nor arrangement for treating the trailing end tail of the bunch winding portion so that the trailing end tail of the bunch winding portion can easily be unwound from the yarn package. Especially for the case that the yarn package is doffed from the yarn package forming machine while rolling on an inclined plate in a direction opposite to the winding direction of the yarn package on the bobbin, the trailing end tail of the yarn is frequently unwound and thus is likely to dangle from the yarn package.
The unwound and dangling trailing end tail of the yarn is apt to cause various problems as follows.
1) While the yarn package is being doffed from the yarn package forming machine, the dangling trailing end tail of the yarn is entangled and clung with other parts or elements of the yarn package forming machine after being severed by these elements or otherwise bringing about stains to the yarn package forming machine. The entanglement and clinging of the yarn with the parts or elements of the yarn package forming machine may entail many cumbersome troubles to following processes and operations of the yarn package forming machine.
2) The efficiency of the operation of the yarn package forming machine may deteriorate resulting from the fact that the dangling trailing end tail of the yarn is liable to be entangled and clung with other objects while the yarn packages are being carried or transferred to the locations at the downstream of this yarn package forming machine.
3) The dangling end of the yarn is required to be tied with another end tail of the yarn of the yarn package by hands of a worker.
It is, therefore, an object of the present invention to provide a yarn package forming method which overcome the above drawbacks inherent in the conventional yarn package forming machine and can eliminate such a dangling trailing end tail of the yarn produced in the conventional yarn package forming machine.
It is another object of the present invention to provide a yarn package forming method which can realize an operation superior to that of the conventional yarn package forming machine.
It is a further object of the present invention to provide a yarn package forming machine which can eliminate troubles inclined to take place during the yarn package doffing operation.